A somehow similar approach has been done some 30+ years ago for an underground train station in Milan, Italy: https://www.rocksoil.com/index.php/it/ricerca-e-s

A somehow similar approach has been done some 30+ years ago for an underground train station in Milan, Italy: https://www.rocksoil.com/index.php/it/ricerca-e-sviluppo/22-ricerca-e-sviluppo/75-arco-cellulare https://www.rocksoil.com/index.php/it/ricerca-e-sviluppo/22-... The bore pipes in that project were much larger though, and became part of the tunnel supporting structure. Besides the small test they showed in this video, the animations look a lot like "pure theory in ideal terrain", very likely this technique, if it will ever be proved actually viable, will be suited to only a few, and very homogenuous, kinds of geology/terrains.